In a display device in which a display area has a plurality of pixels, thin-film transistors (TFTs) are commonly used as switching elements for controlling the charging and discharging in the pixels. At least one driver IC is used to drive the TFT switching elements. A prior art display device is shown in FIG. 1. One of the functions of the driver IC is to receive digital data and transform the digital data into analog signals. Typically the amplitude of the digital data is much smaller than the analog signals. In a liquid crystal display (LCD) panel, the transmission of light through the liquid crystal layer is controlled by an electrical field applied to the liquid crystal layer. The amplitude of the analog signals applied to the pixels, together with the polarizers located on opposite sides of the liquid crystal layer, at least partly controls the brightness levels of the pixels and the gray scale of the display panel. As the image quality of a display device improved, the role of the driver IC becomes more important. In particular, large display panels such as TV screens and computer monitors require a large number of driver ICs.
As shown in FIG. 1, the display device 2 has a substrate 3 for accommodating a display area 4, one or more control circuits 5 and a driver IC 6. The driver IC 6 is configured to receive input signals from a connector, such as a flexible printed circuit (FPC) 7. One of the functions of the driver IC 6 is to provide analog signals indicative of image data to the display area 4, under the control of the control circuit 5. As a driver IC takes up some area of the substrate outside the display area, the substrate must have a border area large enough for the driver ICs.
In smaller display devices, such as personal wearable display devices and information display devices for use on home appliances and office equipment, the image quality is less important. Some of those display devices tend to have a small substrate and the border area outside the display area is relatively small. It would be desirable to eliminate the use of driver ICs in order to minimize the border area.